My iPhone 5 warms up significantly when playing Angry Birds Star Wars. I don't really play any other games and none of my other apps make the phone get hot. I think it's normal with certain games/apps.

Angry Birds Star Wars seems to heat it up more than any other app I currently use. I wonder if there are any iPhone 5s that do not experience any heating when running that game specifically. If it's unanimous that it heats up for everyone, I guess it's just normal and not just a defect with my phone specifically.

I used an IR thermometer to measure both the 4 and 5 when video recording. Don't have the exact numbers in front of me at the moment, but at the hottest point by the camera, the 4 read around 42C and the 5 only 40C. But the rest of the backside was slightly warmer by a degree on the 5. So yeah since the metal back conducts the heat better, it will feel slightly overall warmer, but not by any significant margin over the 4.

Now I'm aware the more you tax it, the warmer it can get, but I don't think the two apps mentioned above would tax the CPU that much.

Anyway, if it's normal then I can live with it but I was wondering whether it's my phone specifically that's experiencing an issue or whether it's just normal thermals for the new iPhone.

My iPhone 4 never got this hot and even when it did warm, it was really graphic intensive stuff only. Never from simple apps like flipboard or angry birds.

Think of it like how the MBPs disperse heat. The heat is transferred from the inside to the outside by using the aluminum as a conduit. It gets how but not uncomfortably hot. My 4th Gen ipod touch was much worse. I have a case on it now so it doesnt bother me but it is normal and part of the reason why Aluminum was used. As chips get more and more powerful they have to find better ways of getting the heat to the outside of the device and using Aluminum is a genius way of doing that.